Complete set: Intro to C - Bill Buchanan

2.9 StreamReader
The StreamReader class allows us to access data from files.
Useful methods of StreamReader:
• ReadLine() returns one line as a string
• Read() returns the ASCII for the next character and consumes it.
• Peek() returns the ASCII for the next character without consuming it.
When we hit the end of file Peek() returns –1 – this is useful to control a while loop
(although not as useful as EOF would have been).
A while loop to print the first non-space character of every line
System.IO.StreamReader fh =
new System.IO.StreamReader(@"..\..\Form1.cs");
while (fh.Peek() != -1)
{
string ln = fh.ReadLine().TrimStart();
if (ln.Length>0)
Console.WriteLine(ln[0]);
}
MessageBox.Show("Done!");
Notes:
• StreamReader is in the System.IO namespace
• ln.Length returns the length of a string
• ln[0] gives the first character of the string ln. We get a run time error if the
string is too short.
Introduction to .NET
Agilent .NET Course: C# Basics 10